[secabeen]

That's an interesting theory that I hadn't seen before. It would require the horizontal rebar in the pool deck to be strong enough that it could pull over the columns, which contrasts with that rebar also being weak enough to collapse. Likewise, in this scenario, would there still be punch-through columns in the parking deck area, instead of those columns falling over too?

The other question that obviously follows from this is, were those columns to fail, why did the failure of the columns on one edge of the building cause the entire section of building to collapse catastrophically? At 1:08 of the simulation, you can see the rest of the columns are still standing under the building.

[XorNot]

Steel is strongest in extension, and a horizontal pulling moment is going through the cross section of the rebar rather then perpendicular to it.

The rebar would have different load bearing capacities in different directions, particularly if it was rusting (i.e. most likely the corrosion was principally on the top face).